| 1. |
- Aftab, Obaid, 1984-, et al.
(författare)
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NMR spectroscopy based metabolic profiling of drug induced changes in vitro can discriminate between pharmacological classes
- 2014
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Ingår i: Journal of chemical information and modeling. - : American Chemical Society (ACS). - 1549-9596 .- 1549-960X. ; 54:11, s. 3251-3258
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Tidskriftsartikel (refereegranskat)abstract
- Drug induced changes in mammalian cell line models have already been extensively profiled at the systemic mRNA level and subsequently used to suggest mechanisms of action for new substances as well as to support drug repurposing, i.e. identifying new potential indications for drugs already licensed for other pharmacotherapy settings. The seminal work in this field, which includes a large database and computational algorithms for pattern matching, is known as the “Connectivity Map” (CMap). The potential of similar exercises at the metabolite level is, however, still largely unexplored. Only recently the first high throughput metabolomic assay pilot study was published, involving screening of metabolic response to a set of 56 kinase inhibitors in a 96-well format. Here we report results from a separately developed metabolic profiling assay, which leverages 1H NMR spectroscopy to the quantification of metabolic changes in the HCT116 colorectal cancer cell line, in response to each of 26 compounds. These agents are distributed across 12 different pharmacological classes covering a broad spectrum of bioactivity. Differential metabolic profiles, inferred from multivariate spectral analysis of 18 spectral bins, allowed clustering of most tested drugs according to their respective pharmacological class. A more advanced supervised analysis, involving one multivariate scattering matrix per pharmacological class and using only 3 spectral bins (three metabolites), showed even more distinct pharmacology-related cluster formations. In conclusion, this kind of relatively fast and inexpensive profiling seems to provide a promising alternative to that afforded by mRNA expression analysis, which is relatively slow and costly. As also indicated by the present pilot study, the resulting metabolic profiles do not seem to provide as information rich signatures as those obtained using systemic mRNA profiling, but the methodology holds strong promise for significant refinement.
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| 2. |
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| 3. |
- Amini, Ahmad, et al.
(författare)
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Principles for different modes of multiple-injection CZE
- 2008
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 29:19, s. 3952-3958
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces four different modes of multiple-injection CZE (MICZE). The validity of these MICZE models was evaluated by the experimental data. Prior to the application of MICZE, the electrophoretic conditions are developed in the single-injection mode by adjusting different experimental parameters such as pH, type and concentration of buffer additives and temperature. Based on the migration time difference (tmig) between the analyte and the internal standard or injection marker, one or more MICZE modes can be employed. The injection marker is added to the sample to compensate for injection-volume fluctuations. The inter-plug distance is regulated by applying an electrical field over the capillary for a short period of time between each injection. After the final injection, the separation is completed by electrophoresis for a time period corresponding to that in the single-injection mode
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| 4. |
- Arvidsson, Anna K., 1971-, et al.
(författare)
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Nya regler för en effektivare vinterväghållning : En förstudie
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Idag kostar vinterväghållningen årligen cirka 2 miljarder, men det saknas bra uppföljningsverktyg för att se hur dessa pengar fördelas. Detta notat summerar hur inrapportering, regelverk för vintervägsåtgärder och ersättningsmodeller fungerar idag samt diskuterar vilken nyutvecklad teknik som skulle kunna användas framöver för att optimera vinterväghållningen. Det svenska VägVäderinformationsSystemet (VViS) introducerades som hjälpmedel för vinterväghållning under slutet av 1970-talet och har under 80- och 90-talet byggts ut och idag finns det cirka 800 stationer på de statliga svenska vägarna. De mäter bland annat temperaturen i luften och vägytan, vindriktning och vindhastighet, de detekterar nederbördstyp och mängd och på många av stationerna finns det även kameror för bedömning av väglag. Information från VViS används idag, tillsammans med väderprognoser, som det huvudsakliga beslutsunderlaget för att bestämma behovet av vinterväghållningsåtgärder. Syftet med denna förstudie har varit att ta fram ett underlag till ett nytt regelverk för när åtgärder behöver utföras för att få en bra vägstandard på vintern och hur ersättningen ska kunna regleras i förhållande till detta, för att få en effektivare vinterväghållning. Den tekniska utvecklingen har gått framåt de senaste åren inom en rad olika områden, till exempel bilindustrin och när det gäller beröringsfria sensorer för mätning av bland annat friktion och vägytetemperatur. De nya teknikerna kan kopplas samman och tillsammans med VViS skulle det kunna ge en mer tydlig bild av när och var åtgärder behövs för att få den mest effektiva vinterväghållningen. Detta skulle även kunna användas för att utforma ett beslutsstödsystem för att underlätta entreprenörernas arbete.
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| 5. |
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| 6. |
- Bekiroglu, Somer, et al.
(författare)
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Validation of a quantitative NMR method for suspected counterfeit products exemplified on determination of benzethonium chloride in grapefruit seed extracts
- 2008
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 47:4-5, s. 958-961
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Tidskriftsartikel (refereegranskat)abstract
- A H-1-nuclear magnetic resonance (NMR) spectroscopy method for quantitative determination of benzethonium chloride (BTC) as a constituent of grapefruit seed extract was developed. The method was validated, assessing its specificity, linearity, range, and precision, as well as accuracy, limit of quantification and robustness. The method includes quantification using an internal reference standard, 1,3,5-trimethoxybenzene, and regarded as simple, rapid, and easy to implement. A commercial grapefruit seed extract was studied and the experiments were performed on spectrometers operating at two different fields, 300 and 600 MHz for proton frequencies, the former with a broad band (BB) probe and the latter equipped with both a BB probe and a CryoProbe (TM). The concentration average for the product sample was 78.0, 77.8 and 78.4 mg/ml using the 300 BB probe, the 600 MHz BB probe and CryoProbe (TM), respectively. The standard deviation and relative standard deviation (R.S.D., in parenthesis) for the average concentrations was 0.2 (0.3%), 0.3 (0.4%) and 0.3 mg/ml (0.4%), respectively.
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| 7. |
- Björck, Lennart, et al.
(författare)
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Tveksam vinst med ekolantbruk
- 2009
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Ingår i: Svenska dagbladet. - 1101-2412. ; -
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 8. |
- Elmsjö, Albert, et al.
(författare)
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Method selectivity evaluation using the co-feature ratio in LC/MS metabolomics : Comparison of HILIC stationary phase performance for the analysis of plasma, urine and cell extracts.
- 2018
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1568, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of the chromatographic separation in metabolomics studies has primarily been done using preselected sets of standards or by counting the number of detected features. An alternative approach is to calculate each feature's co-feature ratio, which is a combined selectivity measurement for the separation (i.e. extent of co-elution) and the MS-signal (i.e. adduct formation and in-source fragmentation). The aim of this study was to demonstrate how the selectivity of different HILIC stationary phases can be evaluated using the co-feature ratio approach. The study was based on three sample types; plasma, urine and cell extracts. Samples were analyzed on an UHPLC-ESI-Q-ToF system using an amide, a bare silica and a sulfobetaine stationary phase. For each feature, a co-feature ratio was calculated and used for multivariate analysis of the selectivity differences between the three stationary phases. Unsupervised PCA models indicated that the co-feature ratios were highly dependent on type of stationary phase. For several metabolites a 15-30 fold difference in the co-feature ratio were observed between the stationary phases. Observed selectivity differences related primarily to the retention patterns of unwanted matrix components such as inorganic salts (detected as salt clusters), glycerophospholipids, and polyethylene glycols. These matrix components affected the signal intensity of co-eluting metabolites by interfering with the ionization efficiency and/or their adduct formation. Furthermore, the retention pattern of these matrix components had huge influence on the number of detected features. The co-feature ratio approach has successfully been applied for evaluation of the selectivity performance of three HILIC stationary phases. The co-feature ratio could therefore be used in metabolomics for developing selective methods fit for their purpose, thereby avoiding generic analytical approaches, which are often biased, as type and amount of interfering matrix components are metabolome dependent.
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| 9. |
- Elmsjö, Albert, et al.
(författare)
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NMR-based metabolic profiling in healthy individuals overfed different types of fat : links to changes in liver fat accumulation and lean tissue mass.
- 2015
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Ingår i: Nutrition & Diabetes. - : Springer Science and Business Media LLC. - 2044-4052. ; 5:19, s. e182-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Overeating different dietary fatty acids influence the amount of liver fat stored during weight gain, however, the mechanisms responsible are unclear. We aimed to identify non-lipid metabolites that may differentiate between saturated (SFA) and polyunsaturated fatty acid (PUFA) overfeeding using a non-targeted metabolomic approach. We also investigated the possible relationships between plasma metabolites and body fat accumulation.METHODS: In a randomized study (LIPOGAIN study), n=39 healthy individuals were overfed with muffins containing SFA or PUFA. Plasma samples were precipitated with cold acetonitrile and analyzed by nuclear magnetic resonance (NMR) spectroscopy. Pattern recognition techniques were used to overview the data, identify variables contributing to group classification and to correlate metabolites with fat accumulation.RESULTS: We previously reported that SFA causes a greater accumulation of liver fat, visceral fat and total body fat, whereas lean tissue levels increases less compared with PUFA, despite comparable weight gain. In this study, lactate and acetate were identified as important contributors to group classification between SFA and PUFA (P<0.05). Furthermore, the fat depots (total body fat, visceral adipose tissue and liver fat) and lean tissue correlated (P(corr)>0.5) all with two or more metabolites (for example, branched amino acids, alanine, acetate and lactate). The metabolite composition differed in a manner that may indicate higher insulin sensitivity after a diet with PUFA compared with SFA, but this needs to be confirmed in future studies.CONCLUSION: A non-lipid metabolic profiling approach only identified a few metabolites that differentiated between SFA and PUFA overfeeding. Whether these metabolite changes are involved in depot-specific fat storage and increased lean tissue mass during overeating needs further investigation.
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| 10. |
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| 11. |
- Elmsjö, Albert, 1986-
(författare)
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Selectivity in NMR and LC-MS Metabolomics : The Importance of Sample Preparation and Separation, and how to Measure Selectivity in LC-MS Metabolomics.
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Until now, most metabolomics protocols have been optimized towards high sample throughput and high metabolite coverage, parameters considered to be highly important for identifying influenced biological pathways and to generate as many potential biomarkers as possible. From an analytical point of view this can be troubling, as neither sample throughput nor the number of signals relates to actual quality of the detected signals/metabolites. However, a method’s selectivity for a specific signal/metabolite is often closely associated to the quality of that signal, yet this is a parameter often neglected in metabolomics.This thesis demonstrates the importance of considering selectivity when developing NMR and LC-MS metabolomics methods, and introduces a novel approach for measuring chromatographic and signal selectivity in LC-MS metabolomics.Selectivity for various sample preparations and HILIC stationary phases was compared. The choice of sample preparation affected the selectivity in both NMR and LC-MS. For the stationary phases, selectivity differences related primarily to retention differences of unwanted matrix components, e.g. inorganic salts or glycerophospholipids. Metabolites co-eluting with these matrix components often showed an incorrect quantitative signal, due to an influenced ionization efficiency and/or adduct formation.A novel approach for measuring selectivity in LC-MS metabolomics has been introduced. By dividing the intensity of each feature (a unique mass at a specific retention time) with the total intensity of the co-eluting features, a ratio representing the combined chromatographic (amount of co-elution) and signal (e.g. in-source fragmentation) selectivity is acquired. The calculated co-feature ratios have successfully been used to compare the selectivity of sample preparations and HILIC stationary phases.In conclusion, standard approaches in metabolomics research might be unwise, as each metabolomics investigation is often unique. The methods used should be adapted for the research question at hand, primarily based on any key metabolites, as well as the type of sample to be analyzed. Increased selectivity, through proper choice of analytical methods, may reduce the risks of matrix-associated effects and thereby reduce the false positive and false negative discovery rate of any metabolomics investigation.
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| 12. |
- Elmsjö, Albert, et al.
(författare)
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The co-feature ratio, a novel method for the measurement of chromatographic and signal selectivity in LC-MS-based metabolomics.
- 2017
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 956, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of analytical procedures, especially in regards to measuring chromatographic and signal selectivity, is highly challenging in untargeted metabolomics. The aim of this study was to suggest a new straightforward approach for a systematic examination of chromatographic and signal selectivity in LC-MS-based metabolomics. By calculating the ratio between each feature and its co-eluting features (the co-features), a measurement of the chromatographic selectivity (i.e. extent of co-elution) as well as the signal selectivity (e.g. amount of adduct formation) of each feature could be acquired, the co-feature ratio. This approach was used to examine possible differences in chromatographic and signal selectivity present in samples exposed to three different sample preparation procedures. The capability of the co-feature ratio was evaluated both in a classical targeted setting using isotope labelled standards as well as without standards in an untargeted setting. For the targeted analysis, several metabolites showed a skewed quantitative signal due to poor chromatographic selectivity and/or poor signal selectivity. Moreover, evaluation of the untargeted approach through multivariate analysis of the co-feature ratios demonstrated the possibility to screen for metabolites displaying poor chromatographic and/or signal selectivity characteristics. We conclude that the co-feature ratio can be a useful tool in the development and evaluation of analytical procedures in LC-MS-based metabolomics investigations. Increased selectivity through proper choice of analytical procedures may decrease the false positive and false negative discovery rate and thereby increase the validity of any metabolomic investigation.
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| 13. |
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| 14. |
- Engskog, Mikael K. R., et al.
(författare)
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LC-MS based global metabolite profiling : the necessity of high data quality
- 2016
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Ingår i: Metabolomics. - : Springer Science and Business Media LLC. - 1573-3882 .- 1573-3890. ; 12:7
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Forskningsöversikt (refereegranskat)abstract
- LC-MS based global metabolite profiling currently lacks detailed guidelines to demonstrate that the obtained data is of high enough analytical quality. Insufficient data quality may result in the failure to generate a hypothesis, or in the worst case, a false or skewed hypothesis. After assessing the literature, it is apparent that an analytically focused summary and critical discussion related to this subject would be beneficial for both beginners and experts engaged in this field. A particular focus will be placed on data quality, which we here define as the degree to which a set of parameters fulfills predetermined criteria, similar to the established guidelines for targeted analysis. However, several of these parameters are difficult to assess since holistic approaches measure thousands of metabolites in parallel and seldom include predefined knowledge of which metabolites will differ between sample groups. In this review, the following parameters will be discussed in detail: reproducibility, selectivity, certainty of metabolite identification and metabolite coverage. The review systematically describes the generic workflow for LC-MS based global metabolite profiling and highlights how each separate part may affect data quality. The last part of the review describes how data quality can be evaluated as well as identifies areas where additional improvement is needed. In this review, we provide our own analytical opinions in regards to evaluation and, to some extent, improvement of data quality.
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| 15. |
- Engskog, Mikael K R, et al.
(författare)
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Metabolic profiling of epithelial ovarian cancer cell lines : evaluation of harvesting protocols for profiling using NMR spectroscopy
- 2015
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Ingår i: Bioanalysis. - : Future Science Ltd. - 1757-6180 .- 1757-6199. ; 7:2, s. 157-166
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Metabolic profiling represents a novel technology for analyzing tumor cells. Epithelial ovarian carcinoma has a low survival rate due to the development of aggressive and chemotherapy-resistant cells. A tailored and reliable protocol is presented for profiling of chemoresistant cells using the cell line SKOV3 and a multiresistant subline SKOV3R.RESULTS: Harvesting protocols with cold methanol or MilliQ freeze/thaw cycles were compared. Increased reproducibility using MilliQ was evidenced. Importantly, both approaches resulted in similar profiles. Compared with parental SKOV3, the SKOV3R cells showed a significantly different profile.CONCLUSION: The MilliQ protocol is preferred owing to higher reproducibility and increased sample preparation options. The resulting metabolic profiles summarize metabolic alterations in chemoresistant cells consistent with a progressed and aggressive phenotype.
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| 16. |
- Engskog, Mikael K R, et al.
(författare)
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The cyanobacterial amino acid beta-N-methylamino-L-alanine perturbs the intermediary metabolism in neonatal rats
- 2013
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Ingår i: Amino Acids. - : Elsevier BV. - 0939-4451 .- 1438-2199. ; 49:5, s. 905-919
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Tidskriftsartikel (refereegranskat)abstract
- The neurotoxic amino acid β-N-methylamino-l-alanine (BMAA) is produced by most cyanobacteria. BMAA is considered as a potential health threat because of its putative role in neurodegenerative diseases. We have previously observed cognitive disturbances and morphological brain changes in adult rodents exposed to BMAA during the development. The aim of this study was to characterize changes of major intermediary metabolites in serum following neonatal exposure to BMAA using a non-targeted metabolomic approach. NMR spectroscopy was used to obtain serum metabolic profiles from neonatal rats exposed to BMAA (40, 150, 460mg/kg) or vehicle on postnatal days 9-10. Multivariate data analysis of binned NMR data indicated metabolic pattern differences between the different treatment groups. In particular five metabolites, d-glucose, lactate, 3-hydroxybutyrate, creatine and acetate, were changed in serum of BMAA-treated neonatal rats. These metabolites are associated with changes in energy metabolism and amino acid metabolism. Further statistical analysis disclosed that all the identified serum metabolites in the lowest dose group were significantly (p<0.05) decreased. The neonatal rat model used in this study is so far the only animal model that displays significant biochemical and behavioral effects after a low short-term dose of BMAA. The demonstrated perturbation of intermediary metabolism may contribute to BMAA-induced developmental changes that result in long-term effects on adult brain function.
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| 17. |
- Engskog, Mikael K. R., et al.
(författare)
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β-N-Methylamino-L-alanine (BMAA) perturbs alanine, aspartate and glutamate metabolism pathways in human neuroblastoma cells as determined by metabolic profiling
- 2017
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Ingår i: Amino Acids. - : Springer Science and Business Media LLC. - 0939-4451 .- 1438-2199. ; 49:5, s. 905-919
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Tidskriftsartikel (refereegranskat)abstract
- β-Methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid that induces long-term cognitive deficits, as well as an increased neurodegeneration and intracellular fibril formation in the hippocampus of adult rodents following short-time neonatal exposure and in vervet monkey brain following long-term exposure. It has also been proposed to be involved in the etiology of neurodegenerative disease in humans. The aim of this study was to identify metabolic effects not related to excitotoxicity or oxidative stress in human neuroblastoma SH-SY5Y cells. The effects of BMAA (50, 250, 1000 µM) for 24 h on cells differentiated with retinoic acid were studied. Samples were analyzed using LC-MS and NMR spectroscopy to detect altered intracellular polar metabolites. The analysis performed, followed by multivariate pattern recognition techniques, revealed significant perturbations in protein biosynthesis, amino acid metabolism pathways and citrate cycle. Of specific interest were the BMAA-induced alterations in alanine, aspartate and glutamate metabolism and as well as alterations in various neurotransmitters/neuromodulators such as GABA and taurine. The results indicate that BMAA can interfere with metabolic pathways involved in neurotransmission in human neuroblastoma cells.
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| 18. |
- Erngren, Ida, et al.
(författare)
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Adduct formation in electrospray ionisation-mass spectrometry with hydrophilic interaction liquid chromatography is strongly affected by the inorganic ion concentration of the samples
- 2019
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Ingår i: Journal of Chromatography A. - : ELSEVIER SCIENCE BV. - 0021-9673 .- 1873-3778. ; 1600, s. 174-182
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Tidskriftsartikel (refereegranskat)abstract
- Hydrophilic interaction liquid chromatography (HILIC)/electrospray ionisation-mass spectrometry (ESI-MS) has gained interest for the analysis of polar analytes in bioanalytical applications in recent years. However, ESI-MS is prone to adduct formation of analytes. In contrast to reversed phase chromatography, small inorganic ions have retention in HILIC, i.e. analytes and inorganic ions may co-elute, which could influence the adduct formation. In the present paper, it was demonstrated that the co-elution of sodium ions or potassium ions and analytes in HILIC/ESI-MS affect the adduct formation and that different concentrations of sodium ions and potassium ions in biological samples could have an impact on the quantitative response of the respective adducts as well as the quantitative response of the protonated adduct. The co-elution also lead to cluster formation of analytes and sodium formate or potassium formate, causing extremely complicated spectra. In analytical applications using HILIC/ESI-MS where internal standards are rarely used or not properly matched, great care needs to be taken to ensure minimal variation of inorganic ion concentration between samples. Moreover, the use of alkali metal ion adducts as quantitative target ions in relative quantitative applications should be made with caution if proper internal standards are not used.
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| 19. |
- Erngren, Ida, 1989-
(författare)
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Analytical method development in liquid chromatography- mass spectrometry based metabolomics
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metabolomics is the analytical field which aims at analyzing all small molecules, metabolites, in a biological system simultaneously. Currently no analytical methods are able to capture the entire metabolome, therefore, the analytical methods are often developed to be as general as possible. However, as research within the metabolomics field is generally driven by biological questions method development is often overlooked. Moreover, method development in metabolomics is very challenging, as evaluation of the methods are difficult since they are not developed for any particular metabolites. Method development is very important though, data quality and accuracy of relative quantitations is paramount if metabolomics is to be used to answer the biological questions at hand.The articles included in the thesis focus around both analytical method development and applications of metabolomics. In the first paper, head and neck cancer cell lines with different sensitivity to ionizing radiation was investigated using LC-MS based metabolomics. A theory on how the radiation resistant (UM-SCC-74B) cell line could alter its metabolism to handle redox status, DNA repair and DNA methylation was formulated. In the second article the sampling of sponge samples (Geodia barretti) was investigated with regard to its effects on detected metabolite profiles and data quality. It was found that freezing the samples directly was the best alternative which allowed for analysis of most metabolite classes. Storing the samples in solvent lead to a substantial extraction of metabolites to the solvent. For metabolomics, the solvents were more useful than the actual sponge samples that had been stored in solvent. In article three the problems caused by high concentrations of inorganic ions in biological samples in HILIC-ESI-MS analyses was described. The inorganic ions can affect relative quantitation and lead to erroneous results and overly complicated datasets inflated by the extra signals caused by cluster formation. To mitigate the problems caused by the inorganic ions a sample preparation method was developed in article four. The method used cation exchange SPE to trap alkali metal ions which, resulted in less ion-suppression, higher signal intensities of relevant metabolites as well as reduced adduct and cluster formation.In conclusion, this thesis have described projects where metabolomics have been applied to answer biological questions as well as analytical method development in LC-MS based metabolomics. Limitations with current methods was described and possible solutions to improve the methods has been presented.
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| 20. |
- Haglind, Alfred, 1986-
(författare)
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Determination of the Environmental Fate of Drug Substances and the Matrix Effects of Complex Samples in SFC/ESI-MS
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Awareness of the potential problems caused by drug compounds in the environment has increased over the last decade, both among researchers and with the public. This thesis describes the development of analytical methods and their application to wetlands constructed for purification of wastewater from e.g. drug compounds. Different wetlands were investigated using microcosm-models, to determine their biodegradation. An enantioselective and sensitive SFC/ESI-QqQ method was developed and validated for the enantiomeric separation of atenolol, metoprolol, propranolol and metoprolol acid. It was applied measuring the enantiomeric fraction of the compounds in three different microcosm-models. The same microcosms were also used to investigate the transformation products formed in these wetlands. In this work, LC/ESI-QToF was used to identify the transformation products using standard references, the original compounds or analogs, comparing their accurate mass and product ions. One not previously observed major transformation product identified from propranolol were 1-naphthol. Several minor transformation products were also identified, showing how diverse the formation might be in wetlands.A second part compares the matrix effect of ESI/MS using SFC and reversed phase LC, utilizing general screening methods for drug compounds in plasma, horse urine and influent/effluent wastewater. These matrices are known to suffer from matrix effects when using the ESI-source, and if SFC would suffer less than LC it could be a great benefit. The matrix profiles showed that this is likely not the case: although SFC was affected by different interferences then LC. One example is the formation of clusters causing major ion suppression. This unique SFC-phenomenon was investigated further, showing that metal ions were separated and eluted at different retention times, forming clusters in the ion source between metal ions and the organic modifier and/or make-up solvent.In conclusion, the first part of this thesis describes analytical methods for determination of drug compounds in the environment, using LC and SFC, connected to both high and low resolving MS. The second part focuses on fundamental analytical chemistry, comparing the matrix effects of SFC/ESI-MS with LC/ESI-MS, and investigates the cluster phenomena observed for samples containing alkali ions and an organic modifier in the mobile phase in SFC/ESI-MS.
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| 21. |
- Haglind, Alfred, 1986-, et al.
(författare)
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Major signal suppression from metal ion clusters in SFC/ESI-MS : Cause and Effects
- 2018
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1084, s. 96-105
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Tidskriftsartikel (refereegranskat)abstract
- The widening application area of SFC-MS with polar analytes and water-containing samples facilitates the use of quick and simple sample preparation techniques such as “dilute and shoot” and protein precipitation. This has also introduced new polar interfering components such as alkali metal ions naturally abundant in e.g. blood plasma and urine, which have shown to be retained using screening conditions in SFC/ESI-TOF-MS and causing areas of major ion suppression. Analytes co-eluting with these clusters will have a decreased signal intensity, which might have a major effect on both quantification and identification. When investigating the composition of the alkali metal clusters using accurate mass and isotopic pattern, it could be concluded that they were previously not described in the literature. Using NaCl and KCl standards and different chromatographic conditions, varying e.g. column and modifier, the clusters proved to be formed from the alkali metal ions in combination with the alcohol modifier and make-up solvent. Their compositions were [(XOCH3)n+X]+, [(XOH)n+X]+, [(X2CO3)n+X]+ and [(XOOCOCH3)n+X]+ for X= Na+ or K+ in ESI+. In ESI-, the clusters depended more on modifier, with [(XCl)n+Cl]- and [(XOCH3)n+OCH3]- mainly formed in pure methanol and [(XOOCH)n+OOCH]- when 20 mM NH4Fa was added.To prevent the formation of the clusters by avoiding methanol as modifier might be difficult, as this is a widely used modifier providing good solubility when analyzing polar compounds in SFC. A sample preparation with e.g. LLE would remove the alkali ions, however also introducing a time consuming and discriminating step into the method. Since the alkali metal ions were retained and affected by chromatographic adjustments as e.g. mobile phase modifications, a way to avoid them could therefore be chromatographic tuning, when analyzing samples containing them.
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| 22. |
- Häggblad Sahlberg, Sara, 1980-, et al.
(författare)
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Different functions of AKT1 and AKT2 in molecular pathways, cell migration and metabolism in colon cancer cells
- 2017
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Ingår i: International Journal of Oncology. - : Spandidos Publications. - 1019-6439 .- 1791-2423. ; 50:1, s. 5-14
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Tidskriftsartikel (refereegranskat)abstract
- AKT is a central protein in many cellular pathways such as cell survival, proliferation, glucose uptake, metabolism, angiogenesis, as well as radiation and drug response. The three isoforms of AKT (AKT1, AKT2 and AKT3) are proposed to have different physiological functions, properties and expression patterns in a cell type-dependent manner. As of yet, not much is known about the influence of the different AKT isoforms in the genome and their effects in the metabolism of colorectal cancer cells. In the present study, DLD-1 isogenic AKT1, AKT2 and AKT'/2 knockout colon cancer cell lines were used as a model system in conjunction with the parental cell line in order to further elucidate the differences between the AKT isoforms and how they are involved in various cellular pathways. This was done using genome wide expression analyses, metabolic profiling and cell migration assays. In conclusion, downregulation of genes in the cell adhesion, extracellular matrix and Notch-pathways and upregulation of apoptosis and metastasis inhibitory genes in the p53-pathway, confirm that the knockout of both AKT1 and AKT2 will attenuate metastasis and tumor cell growth. This was verified with a reduction in migration rate in the AKT1 KO and AKT2 KO and most explicitly in the AKT1/2 KO. Furthermore, the knockout of AKT1, AKT2 or both, resulted in a reduction in lactate and alanine, suggesting that the metabolism of carbohydrates and glutathione was impaired. This was further verified in gene expression analyses, showing downregulation of genes involved in glucose metabolism. Additionally, both AKT1 KO and AKT2 KO demonstrated an impaired fatty acid metabolism. However, genes were upregulated in the Wnt and cell proliferation pathways, which could oppose this effect. AKT inhibition should therefore be combined with other effectors to attain the best effect.
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| 23. |
- Johansson, Monika, et al.
(författare)
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A general analytical platform and strategy in search for illegal drugs
- 2014
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 100, s. 215-229
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Tidskriftsartikel (refereegranskat)abstract
- An effective screening procedure to identify and quantify active pharmaceutical substances in suspected illegal medicinal products is described. The analytical platform, consisting of accurate mass determination with liquid chromatography time-of-flight mass spectrometry (LC-QTOF-MS) in combination with nuclear magnetic resonance (NMR) spectroscopy provides an excellent analytical tool to screen for unknowns in medicinal products, food supplements and herbal formulations. This analytical approach has been successfully applied to analyze thousands of samples. The general screening method usually starts with a methanol extraction of tablets/capsules followed by liquid chromatographic separation on a Halo Phenyl-Hexyl column (2.7μm; 100mm×2.1mm) using an acetonitrile/0.1% formic acid gradient as eluent. The accurate mass of peaks of interest was recorded and a search made against an in-house database containing approximately 4200 substances, mostly pharmaceutical compounds. The search could be general or tailored against different classes of compounds. Hits were confirmed by analyzing a reference substance and/or by NMR. Quantification was normally performed with quantitative NMR (qNMR) spectroscopy. Applications for weight-loss substances like sibutramine and orlistat, sexual potency enhancement (PDE-5 inhibitors), and analgesic drugs are presented in this study. We have also identified prostaglandin analogues in eyelash growth serum, exemplified by isopropyl cloprostenate and bimatoprost. For creams and ointments, matrix solid-phase dispersion (MSPD) was found to give a clean extracts with high recovery prior to LC-MS analyses. The structural elucidation of cetilistat, a new weight-loss substance recently found in illegal medicines purchased over the Internet, is also presented.
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| 24. |
- Lindell Jonsson, Eva, et al.
(författare)
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Exploring Radiation Response in Two Head and Neck Squamous Carcinoma Cell Lines Through Metabolic Profiling
- 2019
-
Ingår i: Frontiers in Oncology. - : Frontiers Media SA. - 2234-943X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Head and neck squamous cell carcinoma (HNSCC) is the sixth most common form of cancer worldwide. Radiotherapy, with or without surgery, represents the major approach to curative treatment. However, not all tumors are equally sensitive to irradiation. It is therefore of interest to apply newer system biology approaches (e.g., metabolic profiling) in squamous cancer cells with different radiosensitivities in order to provide new insights on the mechanisms of radiation response. In this study, two cultured HNSCC cell lines from the same donor, UM-SCC-74A and UM-SCC-74B, were first genotyped using Short Tandem Repeat (STR), and assessed for radiation response by the means of clonogenic survival and growth inhibition assays. Thereafter, cells were cultured, irradiated and collected for subsequent metabolic profiling analyses using liquid chromatography-mass spectrometry (LC-MS). STR verified the similarity of UM-SCC-74A and UM-SCC-74B cells, and three independent assays proved UM-SCC-74B to be clearly more radioresistant than UM-SCC-74A. The LC-MS metabolic profiling demonstrated significant differences in the intracellular metabolome of the two cell lines before irradiation, as well as significant alterations after irradiation. The most important differences between the two cell lines before irradiation were connected to nicotinic acid and nicotinamide metabolism and purine metabolism. In the more radiosensitive UM-SCC-74A cells, the most significant alterations after irradiation were linked to tryptophan metabolism. In the more radioresistant UM-SCC-74B cells, the major alterations after irradiation were connected to nicotinic acid and nicotinamide metabolism, purine metabolism, the methionine cycle as well as the serine, and glycine metabolism. The data suggest that the more radioresistant cell line UM-SCC-74B altered the metabolism to control redox-status, manage DNA-repair, and change DNA methylation after irradiation. This provides new insights on the mechanisms of radiation response, which may aid future identification of biomarkers associated with radioresistance of cancer cells.
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| 25. |
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| 26. |
- Lodén, Henrik, et al.
(författare)
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Quantitative determination of salbutamol in tablets by multiple-injection capillary zone electrophoresis
- 2008
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1207:1-2, s. 181-185
-
Tidskriftsartikel (refereegranskat)abstract
- A multiple-injection capillary zone electrophoresis (MICZE) method has been developed for the assay of salbutamol in Ventoline Depot tablets (GlaxoSmithKline). In the developed method, seven sample sets, each consisting of three samples, were sequentially injected into the capillary and analyzed within a single run. This enabled a total of twenty-one sequential injections, i.e., six standards and fifteen samples, containing salbutamol and the injection marker oxprenolol. The injected sample plugs were separated by plugs of background electrolyte, through application of a short-term voltage (30 kV) over the capillary for different time periods, i.e., tPE1 and tPE2. The samples in each set were isolated from each other by partial electrophoresis for 2.35 min (tPE1), while the sample sets were separated for 10.50 min (tPE2). After the final injection, all the applied samples were subjected to electrophoresis for a time period corresponding to that in conventional single-injection CZE. The method was validated regarding linearity, accuracy, precision and robustness before it was applied to the determination of salbutamol in 15 tablets of Ventoline Depot with a labeled content of 8 mg salbutamol. The average salbutamol content was determined to 7.8 mg (±0.3 mg) from simultaneous analyses of the 15 different tablets.
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| 27. |
- Lodén, Henrik, 1972-
(författare)
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Separation of Pharmaceuticals by Capillary Electrophoresis using Partial Filling and Multiple-injections
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Different multiple-injection methodologies and the partial filling technique (PFT) have been utilized for separation of pharmaceuticals by capillary elec-trophoresis. In multiple-injection capillary zone electrophoresis (MICZE), the samples and all standards, used for construction of the calibration curve, are analyzed within a single run. Four different modes of MICZE have been described by means of equations, which were experimentally verified. The developed equations facilitate the transfer from conventional single-injection CZE to one or more of these MICZE-modes, depending on the selectivity between the analyte and the injection marker. The applicability of two of these modes was then demonstrated by quantification of buserelin and salbutamol, re-spectively in commercially available pharmaceutical products. The content of buserelin in an injection solution was determined to 0.94 mg/ml, which only deviated slightly from the declared concentration (1 mg/ml). An alter-native mode of MICZE, offering a higher number of sequential sample injec-tions, was then utilized for single-run determination of salbutamol in 15 tab-lets, with a labelled content of 8 mg. The average content of the tablets was determined to 7.8 mg, with an intra-tablet variation of 3 % or less. Moreover, UV- and mass-spectrometric detection of enantiomeric amines, resolved by non-aqueous capillary electrophoresis (NACE), was demon-strated. Separation of enantiomeric amines was achieved using the chiral selector (-)-2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid, (-)-DIKGA. Introduction of the non-volatile (-)-DIKGA into the mass-spectrometer was avoided by using the PFT, where the capillary is only partially filled with electrolyte containing the chiral selector.
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| 28. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Multidisciplinary Cooling Design Tool for Electric Vehicle SiC Inverters Utilizing Transient 3D-CFD Computations
- 2021
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Ingår i: eTransportation. - : Elsevier BV. - 2590-1168. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a new design tool that can be used for the development of a proper cooling component for high-power three-phase SiC module-packs for electric vehicles. Specifically, a multidisciplinary approach of the design process is presented that is based on the accurate electrical, thermal and fluid-mechanics modeling as well as computational testing of a high-power three-phase SiC modulepack under transient-load conditions, so that it can effectively meet the highly-demanding cooling requirements of an electric vehicle inverter. The cooling plate is initially designed by using steady-state based 3D-computational-fluid-dynamic (CFD) tool, as in a conventional method. Then, the proposed design algorithm fine-tunes it through transient 3D-CFD computations by following a specific iterative improvement procedure considering the heat dissipation requirements for the SiC power switches during the official driving cycles for passenger vehicles and during abrupt acceleration tests under several ambient environments. Therefore, not only overheating at all operating conditions is avoided, but also, accurate thermal modeling of the individual inverter modules is provided that can be used for lifetime estimations and for calculating the overload capability of the inverter. The design improvement attained with the proposed procedure against the conventional steady-state approach is validated on a traction 450 A SiC inverter with the model of a real passenger vehicle.
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| 29. |
- Niklison-Chirou, Maria Victoria, et al.
(författare)
-
TAp73 is a marker of glutamine addiction in medulloblastoma
- 2017
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Ingår i: Genes & Development. - : COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT. - 0890-9369 .- 1549-5477. ; 31:17, s. 1738-1753
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Tidskriftsartikel (refereegranskat)abstract
- Medulloblastoma is the most common solid primary brain tumor in children. Remarkable advancements in the understanding of the genetic and epigenetic basis of these tumors have informed their recent molecular classification. However, the genotype/phenotype correlation of the subgroups remains largely uncharacterized. In particular, the metabolic phenotype is of great interest because of its druggability, which could lead to the development of novel and more tailored therapies for a subset of medulloblastoma. p73 plays a critical role in a range of cellular metabolic processes. We show overexpression of p73 in a proportion of non-WNT medulloblastoma. In these tumors, p73 sustains cell growth and proliferation via regulation of glutamine metabolism. We validated our results in a xenograft model in which we observed an increase in survival time in mice on a glutamine restriction diet. Notably, glutamine starvation has a synergistic effect with cisplatin, a component of the current medulloblastoma chemotherapy. These findings raise the possibility that glutamine depletion can be used as an adjuvant treatment for p73-expressing medulloblastoma.
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| 30. |
- Pierre, Pernilla Videhult, et al.
(författare)
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Cisplatin-induced metabolome changes in serum : an experimental approach to identify markers for ototoxicity
- 2017
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 137:10, s. 1024-1030
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Ototoxicity from treatment with the anticancer drug cisplatin remains a clinical problem. A wide range of intracellular targets of cisplatin has been found in vivo.AIM: To investigate cisplatin-induced change of the serum metabolite profile and its association with ototoxicity.MATERIAL AND METHODS: Guinea pigs (n = 14) were treated with cisplatin (8 mg/kg b.w., i.v.) 30 min after administration of the otoprotector candidate sodium thiosulfate (group STS; n = 7) or sodium chloride (group NaCl; n = 7). Ototoxicity was evaluated by ABR (3-30 kHz) before and 4 d after drug treatment, and by assessment of hair cell loss. A blood sample was drawn before and 4 d after drug treatment and the polar metabolome in serum was analyzed using LC-MS.RESULTS: Cisplatin-treatment caused significant threshold elevations and outer hair cell (OHC) loss in both groups. The ototoxicity was generally lower in group STS, but a significant difference was reached only at 30 kHz (p = .007). Cisplatin treatment altered the metabolite profile significantly and similarly in both groups. A significant inverse correlation was found between L-acetylcarnitine, N-acetylneuraminic acid, ceramide, and cysteinylserine and high frequency hearing loss in group NaCl. The implication of these correlations should be explored in targeted studies.
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| 31. |
- Pilebro, Björn, et al.
(författare)
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Positron emission tomography (PET) utilizing Pittsburgh compound B (PIB) for detection of amyloid heart deposits in hereditary transthyretin amyloidosis (ATTR)
- 2018
-
Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1071-3581 .- 1532-6551. ; 25:1, s. 240-248
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: DPD scintigraphy has been advocated for imaging cardiac amyloid in ATTR amyloidosis. PET utilizing (11)C-Pittsburgh compound B (PIB) is the gold standard for imaging brain amyloid in Alzheimer's disease. PIB was recently shown to identify cardiac amyloidosis in both AL and ATTR amyloidosis. In the ATTR population, two types of amyloid fibrils exist, one containing fragmented and full-length TTR (type A) and the other only full-length TTR (type B). The aim of this study was to further evaluate PIB-PET in patients with hereditary ATTR amyloidosis.METHODS: Ten patients with biopsy-proven V30M ATTR amyloidosis and discrete or no signs of cardiac involvement were included. Patients were grouped according to TTR-fragmentation. All underwent DPD scintigraphy, echocardiography, and PIB-PET. A left ventricular PIB-retention index (PIB-RI) was established and compared to five normal volunteers.RESULTS: PIB-RI was increased in all patients (P < 0.001), but was significantly higher in type B than in type A (0.129 ± 0.041 vs 0.040 ± 0.006 min(-1), P = 0.009). Cardiac DPD uptake was elevated in group A and absent in group B.CONCLUSION: PIB-PET, in contrast to DPD scintigraphy, has the potential to specifically identify cardiac amyloid depositions irrespective of amyloid fibril composition. The heart appears to be a target organ for amyloid deposition in ATTR amyloidosis.
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| 32. |
- Pirttilä, Kristian, et al.
(författare)
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An LCMS-based untargeted metabolomics protocol for cochlear perilymph : highlighting metabolic effects of hydrogen gas on the inner ear of noise exposed Guinea pigs
- 2019
-
Ingår i: Metabolomics. - : Springer Science and Business Media LLC. - 1573-3882 .- 1573-3890. ; 15:10
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction Noise-induced hearing loss (NIHL) is an increasing problem in society and accounts for a third of all cases of acquired hearing loss. NIHL is caused by formation of reactive oxygen species (ROS) in the cochlea causing oxidative stress. Hydrogen gas (H-2) can alleviate the damage caused by oxidative stress and can be easily administered through inhalation.Objectives To present a protocol for untargeted metabolomics of guinea pig perilymph and investigate the effect of H-2 administration on the perilymph metabolome of noise exposed guinea pigs.Methods The left ear of guinea pigs were exposed to hazardous impulse noise only (Noise, n = 10), noise and H-2 (Noise + H2, n = 10), only H-2 (H2, n = 4), or untreated (Control, n = 2). Scala tympani perilymph was sampled from the cochlea of both ears. The polar component of the perilymph metabolome was analyzed using a HILIC-UHPLC-Q-TOF-MS-based untargeted metabolomics protocol. Multivariate data analysis (MVDA) was performed separately for the exposed- and unexposed ear.Results MVDA allowed separation of groups Noise and Noise + H2 in both the exposed and unexposed ear and yielded 15 metabolites with differentiating relative abundances. Seven were found in both exposed and unexposed ear data and included two osmoprotectants. Eight metabolites were unique to the unexposed ear and included a number of short-chain acylcarnitines.Conclusions A HILIC-UHPLC-Q-TOF-MS-based protocol for untargeted metabolomics of perilymph is presented and shown to be fit-for-purpose. We found a clear difference in the perilymph metabolome of noise exposed guinea pigs with and without H-2 treatment.
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| 33. |
- Pirttilä, Kristian, 1986-
(författare)
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Development of analytical methods for the determination of the small molecule component of complex biological systems
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The research field of untargeted metabolomics aims to determine the relative abundance of all small metabolites in a biological system in order to find biomarkers or make biological inference with regards to the internal or external stimuli. This is no trivial aim, as the small metabolites are both vast in numbers and extremely diverse in their chemical properties. As such, no single analytical method exist that is able to capture the entire metabolome on its own. In addition, the data generated from such experiments is both immense in volume and very complex. This forces researchers to use algorithmic data processing methods to extract the informative part of this data. Such algorithms are, however, both difficult to parametrize and designed to be highly inclusive, the combination of which often leads to errors. One such algorithm is the peak picking procedures used to find chromatographic peaks in liquid chromatography-mass spectrometry (LC-MS) data.In this thesis, four papers are included that focus both on the development of new methods for sample analysis and data processing as well as the application of such, and other, methods in two interdisciplinary research projects. The first paper describes the development and application of a protocol for LC-MS based untargeted analysis of guinea pig perilymph. The focus of the study was to investigate the biochemical processes underlying the protective effect of hydrogen gas on noise-induced hearing loss (NIHL) in guinea pigs exposed to impulse noise. This study sparked two research projects based on limitations observed during the analytical work. The first limitation was that of limited chemical coverage in the analysis when sample volumes are highly limited. The second paper describes the design and validation of a novel separation method for the sequential analysis of both hydrophilic and lipophilic compounds in biological samples. The second limitation observed was the abundance of false peaks reported by peak picking software. These have a negative effect on both downstream data processing as well as data analysis and metabolite identification. The third paper describes the development of a new algorithm for comprehensive peak characterization in untargeted analytical data with the purpose of filtering such false peaks. Both methods presented in the second and third paper were applied to the analysis of guinea pigs perilymph samples in a follow-up study on the attenuating effect of hydrogen gas on NIHL in guinea pigs exposed to broad band continuous noise.
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| 34. |
- Rundlöf, Torgny, et al.
(författare)
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Survey and qualification of internal standards for quantification by 1H NMR spectroscopy
- 2010
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 52:5, s. 645-651
-
Tidskriftsartikel (refereegranskat)abstract
- In quantitative NMR (qNMR) selection of an appropriate internal standard proves to be crucial. In this study, 25 candidate compounds considered to be potent internal standards were investigated with respect to the ability of providing unique signal chemical shifts, purity, solubility, and ease of use. The 1H chemical shift (δ) values, assignments, multiplicities and number of protons (for each signal), appropriateness (as to be used as internal standards) in four different deuterated solvents (D2O, DMSO-d6, CD3OD, CDCl3) were studied. Taking into account the properties of these 25 internal standards, the most versatile eight compounds (2,4,6-triiodophenol, 1,3,5-trichloro-2-nitrobenzene, 3,4,5-trichloropyridine, dimethyl terephthalate, 1,4-dinitrobenzene, 2,3,5-triiodobenzoic acid, maleic acid and fumaric acid) were qualified using both differential scanning calorimetry (DSC) and NMR spectroscopy employing highly pure acetanilide as the reference standard. The data from these two methods were compared as well as utilized in the quality assessment of the compounds as internal standards. Finally, the selected internal standards were tested and evaluated in a real case of quantitative NMR analysis of a paracetamol pharmaceutical product.
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| 35. |
- Rundlöf, Torgny, et al.
(författare)
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Use and qualification of primary and secondary standards employed in quantitative H-1 NMR spectroscopy of pharmaceuticals
- 2014
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 93:SI, s. 111-117
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Tidskriftsartikel (refereegranskat)abstract
- Standards are required in quantitative NMR (qNMR) to obtain accurate and precise results. In this study acetanilide was established and used as a primary standard. Six other chemicals were selected as secondary standards: 3,4,5-trichloropyridine, dimethylterephthalate, maleic acid, 3-sulfolene, 1,4-bis(trimethylsilyl)benzene, and 1,3,5-trimethoxybenzene. The secondary standards were quantified using the primary standard acetanilide. A protocol for qualification and periodic checks of these secondary standards was developed, and used for evaluation of the stability of the compounds. Periodic monitoring of purity was performed for several years. The purity was higher than 99% for all secondary standards. All standards maintained the initial purity during the time period of monitoring, with very small variations in purity (0.3-0.4%). The selected secondary standards were shown to be suitable qNMR standards and that periodic requalification of the standards by qNMR ensures reliable analytical results. These standards have been used in our laboratory for compliance testing of pharmaceutical active substances and approved medicinal products as well as for analysis of suspected illegal medicines. In total more than 1000 samples have been tested using both internal and external standardization and examples are given.
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| 36. |
- Stenholm, Åke, et al.
(författare)
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Identification of Leachables from Trametes versicolor in Biodegradation Experiments
- 2016
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Ingår i: Trends in Green Chemistry. - : Scitechnol Biosoft Pvt. Ltd.. - 2471-9889. ; 4:1:1
-
Tidskriftsartikel (refereegranskat)abstract
- The transport of fungal-derived compounds from Trametes versicolor to the environment was investigated. Fatty acids and sphingoids were identified at the outlet of a bioreactor containing an acidic nutrient solution and immobilized fungal mycelia. The analyses were conducted using UHPLC-Q-TOF-MS (/MS). Eleven fatty acids, including C20:0, C18:1-OH and C20:0-OH that have not been previously described for this species, were detected. The identities of myristic acid (C14:0), palmitic acid (C16:0) and stearic acid (C18:0) were confirmed using reference standards. Six sphingoids, including Sph (t18:0), Sph (t18:1), Sph (d18:0), Sph (d18:1), Sph (d16:0) and Sph (d16:1), were tentatively identified, and the identities of Sph (d18:0) and Sph (d18:1) were confirmed by reference standards. The findings show that an array of compounds, with concentrations at the μgL-1 level, was easily transported from the fungal mycelia. This is of concern when the investigated species is used in biodegradation experiments of xenobiotics and conclusions are to be drawn on the quality of the treated water. The study thus shows that the chemical composition of water treated with Trametes versicolor is also influenced by the immobilized fungus itself. The lipids that were detected, including fatty acids and sphingoids do not present any threat to the environment since they are not toxic. At μgL-1 concentration levels, they are soluble in water.
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| 37. |
- Stenholm, Åke, et al.
(författare)
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Removal of diclofenac from a non-sterile aqueous system using Trametes versicolor with an emphasis on adsorption and biodegradation mechanisms
- 2019
-
Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 40:19, s. 2460-2472
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the search for procedures through which the xenobiotic pollutant diclofenac can be removed from non-sterile aquatic systems. Specifically, adsorption to solid supports (carriers) in combination with biodegradation by non-immobilized and immobilized white rot fungus Trametes versicolor were investigated. Batch experiments using polyurethane foam (PUF)-carriers resulted in 99.9% diclofenac removal after 4 h, with monolayer adsorption of diclofenac to carrier and glass surfaces accounting for most of the diclofenac decrease. Enzymatic reactions contributed less, accounting for approximately < 0.5% of this decrease. In bioreactor experiments using PUF-carriers, an initial 100% removal was achieved with biodegradation contributing approximately 7%. In batch experiments that utilized polyethylene-carriers with negligible immobilization of Trametes versicolor, a 98% total diclofenac removal was achieved after one week, with a biodegradation contribution of approximately 14%. Five novel enzyme-catalyzed biodegradation products were tentatively identified in the batch-wise and bioreactor experiments using full scan ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry. Both reduction and oxidation products were found, with the contents estimated to be at µg L-1 concentration levels.
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| 38. |
- Stenholm, Åke, et al.
(författare)
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Removal of nonylphenol polyethoxylates by adsorption on polyurethane foam and biodegradation using immobilized Trametes versicolor
- 2020
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 724
-
Tidskriftsartikel (refereegranskat)abstract
- Nonylphenol polyethoxylates (NPEOs) are banned in EU due to their endocrine disrupting properties. In a proof of concept study including continuous reactor lab-scale experiments, polyurethane foam (PUF)-immobilized Trametes versicolor was used to reduce the concentration levels of these compounds in an acidic nutrient solution over an 18-day period. Biodegradation and adsorption were identified as the major removal principles. A 90% removal was achieved by solely biodegradation in an experimental setup in which steady state conditions occurred, including NPEO-saturated glass and PUF surfaces. Biotransformation products containing mono- and di-ethoxylated nonylphenol, nonylphenol (NP1EO, NP2EO, NP) and nonylphenol polyethoxy carboxylates (NPECs) were tentatively identified.The maximum static NPEO adsorption capacity of PUF (determined with Erlenmeyer flask experiment) was calculated to 106 mg g−1, and the adsorption was described by the Langmuir isotherm equation. The corresponding maximum dynamic adsorption capacity (determined by continuous reactor experiment) was 100 mg g−1. These findings show that PUF is an excellent adsorbent to NPEOs. Therefore, PUF can either be used as a stand-alone adsorbent to NPEOs or as an immobilizing agent for Trametes versicolor through which a highly efficient biodegradation of these potentially harmful compounds can be achieved. The findings can be of importance in the search for alternative methods to remove NPEOs in process effluents.
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| 39. |
- Stenholm, Åke, et al.
(författare)
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Removal of toluene diamine and its derivatives frompolyurethane foam using immobilized Trametes versicolor
- 2019
-
Ingår i: Advances in Environmental Biology. - : American-Eurasian Network for Scientific Information (AENSI). - 1995-0756 .- 1998-1066. ; 13:2
-
Tidskriftsartikel (refereegranskat)abstract
- Background: In addition to uses in home furnishings and the construction sector, polyurethane foam (PUF) is also prevalent in medical products such as scaffolds and implants. However, these applications raise concerns for human health as the use of this material can result in exposure to the carcinogenic substance 2,4-toluenediamine (2,4-TDA). The objective of this study was to identify easily extracted PUF-residuals and to study the removal of them in a biodegradation experiment including immobilized Trametes versicolor. Ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry (UHPLC-Q-TOF MS) was used in MS and MS/MS-mode to confirm the identities of PUF-related compounds and follow their concentration changes. Results: Except for 2,4-TDA and 2,6-TDA which were confirmed by standards, previously not reported substances were tentatively identified, among them TDA-dimers. These dimers include homodimers, heterodimers containing 2,4-TDA and 2,6-TDA and compounds that are hydroxylated. The experiments that were performed in an acidic fungal culture revealed a not previously described removal of these compounds below the approximate nM detection limit. The mechanisms behind their removal may include biosorption to fungal mycelia, bioaccumulation, use of them as nutrients or extracellular catabolism. Conclusion: The results of this study not only highlight the ease by which harmful compounds were extracted from the investigated PUF-quality which is used in non-medical applications, but also the possibility to use fungal-based methods to eliminate them. This could be facilitated by an initial extraction of PUF (excluding fungi) followed by a removal of the substances with PUF-immobilized Trametes versicolor.The findings in this study may be of interest to further investigate PUF-residuals in products aimed for medical applications.
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| 40. |
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| 41. |
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| 42. |
- Svan, Alfred, et al.
(författare)
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Identification of transformation products from -blocking agents formed in wetland microcosms using LC-Q-ToF
- 2016
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Ingår i: Journal of Mass Spectrometry. - : Wiley. - 1076-5174 .- 1096-9888. ; 51:3, s. 207-218
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Tidskriftsartikel (refereegranskat)abstract
- Identification of degradation products from trace organic compounds, which may retain the biological activity of the parent compound, is an important step in understanding the long-term effects of these compounds on the environment. Constructed wetlands have been successfully utilized to remove contaminants from wastewater effluent, including pharmacologically active compounds. However, relatively little is known about the transformation products formed during wetland treatment. In this study, three different wetland microcosm treatments were used to determine the biotransformation products of the -adrenoreceptor antagonists atenolol, metoprolol and propranolol. LC/ESI-Q-ToF run in the MSE and MS/MS modes was used to identify and characterize the degradation products through the accurate masses of precursor and product ions. The results were compared with those of a reference standard when available. Several compounds not previously described as biotransformation products produced in wetlands were identified, including propranolol-O-sulfate, 1-naphthol and the human metabolite N-deaminated metoprolol. Transformation pathways were significantly affected by microcosm conditions and differed between compounds, despite the compounds' structural similarities. Altogether, a diverse range of transformation products in wetland microcosms were identified and elucidated using high resolving MS. This work shows that transformation products are not always easily predicted, nor formed via the same pathways even for structurally similar compounds.
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| 43. |
- Svan, Alfred, 1986-, et al.
(författare)
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Matrix effects: Do they differ between SFC/ESI-MS and LC/ESI-MS
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction (120 ord)Supercritical fluid chromatography (SFC) is increasingly used in many fields following the new generation of instruments available on the market, often combined with electrospray ionization mass spectrometry (ESI/MS). New methods are developed and validated, often for samples of complex matrices. Thus, measurements of the matrix effects are sometimes included. Comparisons between SFC/ESI/MS and LC/ESI/MS have previously been performed, often focusing on e.g. sensitivity and separation. However, a systematic and qualitative investigation of the matrix effects achieved using same ion source and mass spectrometer, but different types of chromatography, i.e. SFC or LC, is so far lacking. Methods (120 ord)Effluent wastewater was collected and 100.0 ml was extracted using a generic SPE method (Oasis MCX), evaporated and redissolved in 1.0 ml of water:ACN (1:1). A 10 min gradient was developed for each technique, separating eight compounds chosen for being low molecular weight drugs with varying hydrophobicity and proteolytic properties. The mixture of compounds was then added to the ESI make-up solvent (MeOH) for the SFC/ESI/MS method. The extracted wastewater was injected without added compounds, and the SRM channel for each compound was monitored using tandem quadrupole MS (Quattro Micro, Waters®). The same interface and settings were used for LC, but an infusion of compounds was performed through a post-column syringe pump since no make-up flow was used. Preliminary data – Limit 300 wordsThe retention times for the eight model compounds were evenly spread over the chromatographic time scale for both chromatographic methods. When applying the continuous compound infusion through the make-up solution (SFC/ESI/MS) or through a syringe pump (LC/ESI/MS), a stable signal was observed for all compounds. Injection of the extracted wastewater affected the signal in comparison with the blank. The difference in the signal profiles were however larger between LC and SFC than between blank and extracted wastewater. The two separation techniques also gave different levels of noise and variations in the SRM-channels for the different compounds, and occurred at differently time points during the gradients for both the techniques. In summary, the matrix effects seem to affect the detection differently depending on what chromatographic technique that is used. With increased knowledge about this, it could help future method development to minimize the matrix effects. Novel aspect – Limit 20 wordsThe first systematic comparison between SFC and LC in terms of matrix effects for ESI-MS/MS using qualitative methods (infusion).
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- Svan, Alfred, 1986-, et al.
(författare)
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The differences in matrix effect between supercritical fluid chromatography and reversed phase liquid chromatography coupled to ESI/MS
- 2018
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Ingår i: Analytica Chimica Acta. - : ELSEVIER SCIENCE BV. - 0003-2670 .- 1873-4324. ; 1000, s. 163-171
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Tidskriftsartikel (refereegranskat)abstract
- For many sample matrices, matrix effects are a troublesome phenomenon using the electrospray ionization source. The increasing use of supercritical fluid chromatography with CO2 in combination with the electrospray ionization source for MS detection is therefore raising questions: is the matrix effect behaving differently using SFC in comparison with reversed phase LC? This was investigated using urine, plasma, influent-and effluent-wastewater as sample matrices. The matrix effect was evaluated using the post-extraction addition method and through post-column infusions. Matrix effect profiles generated from the post-column infusions in combination with time of flight-MS detection provided the most valuable information for the study. The combination of both qualitative and semi-quantitative information with the ability to use HRMS-data for identifying interfering compounds from the same experiment was very useful, and has to the authors' knowledge not been used this way before. The results showed that both LC and SFC are affected by matrix effects, however differently depending on sample matrix. Generally, both suppressions and enhancements were seen, with a higher amount of enhancements for LC, where 65% of all compounds and all sample matrices were enhanced, compared to only 7% for SFC. Several interferences were tentatively identified, with phospholipids, creatinine, and metal ion clusters as examples of important interferences, with different impact depending on chromatographic technique. SFC needs a different strategy for limiting matrix interferences, owing to its almost reverse retention order compared to RPLC.
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| 45. |
- Svan, Alfred, 1986-, et al.
(författare)
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The differences in matrix effects between supercritical fluid chromatography and reversed phase liquid chromatography coupled to ESI/MS analyzing blood plasma
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction The increasing popularity of supercritical fluid chromatography (SFC) in combination with electrospray ionization mass spectrometry (ESI/MS) within several fields calls for a deeper knowledge regarding this combination of techniques. The ESI source is known for its sensitivity regarding matrix effects, often a factor controlled during method development and validation using LC. The different chemistry and chromatographic selectivity of LC and SFC give potentially different impact on the ionization process in ESI; however, this an area still not well studied. Aim: To investigate how the matrix effects in ESI/MS differ for human plasma samples between SFC and reversed-phase LC, using generic screening conditions for both techniques, and a set of typical low molecular weight drug substances.Methods Pooled human plasma (500 µl) was precipitated using ice-cold acetonitrile (1000 µl). After mixing and centrifuging, 1200 µl of the supernatant were removed and evaporated at 40 ̊C. When dry, the samples were dissolved in 500µl water+0.1% FA (for LC) or acetonitrile:water 75:25 (for SFC). The samples were analyzed using SFC (Acquity UPC2, Waters®) and LC (Acquity UPLC, Waters®) and general screening conditions, using 10 min gradients. The same MS-system, a Q-ToF (Synapt G2-S, Waters®) acquiring in full scan mode, was used for detection with both separation techniques. The matrix effect was mainly evaluated using the Matrix Effect Profile, achieved from post-column compound infusions and injections of pretreated sample matrix and neat standards. From these data the average ME% was calculated for each data-point in the chromatogram, and through the full-scan mode using ToF, the compounds co-eluting with areas of suppression could be tentatively identified, suspected of creating the suppression. Results and discussion The Matrix Effect Profile-evaluation of the experiments, combining qualitative and quantitative information with the added ability to use HRMS-data to identify interfering compounds from the same experiments were most useful for our aim. Phospholipids, creatinine, polyethylene glycol and cluster formations are examples of important interferences co-eluting with areas of ion suppression, but with different impact depending on chromatographic technique. The results also showed several areas of enhancement using LC, an effect not seen using SFC.
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